Giant snails are helping scientists monitor emissions from a sewage incinerator in St. Petersburg, Russia. If the snails start to inhale too much poisoned air, they’ll get sick and show researchers that there are dangerous toxins in the expelled gas.

"The African snails, which are able to live for up to seven years, will also help to test the influence of possible accumulating substances over a long period," said Sergei Kholodkevich, an ecological researcher who came up with the idea for using the snails, in an article in the Philadelphia Inquirer.

Sensors attached to the snails, which can reach eight inches in length, monitor their heartbeats and other vital signs. Three of the six involved in the project breathe clean air while three inhale fumes that emanate from the wastewater treatment plant’s chimney.

“The plant uses conventional gauges to check emissions, but company officials said they also wanted to keep an eye on compounds that might be produced in concentrations too low for the gauges to detect or that might harm humans when combined with other substances,” the article stated.

The tactic is usual, and one that critics say is just a way to draw attention away from unsafe practices at the plant. Vodokanal, the waterworks company, told a Greenpeace representative that the organization could not inspect the city’s treatment facilities, leading the environmental group to accuse the company of harming the environment.

Hopefully the snails, or the crayfish that the company is using to test the city’s water quality, will indicate if the emissions are noxious or not.